COMMISSION 27 OF THE I. A. U.
             INFORMATION BULLETIN ON VARIABLE STARS
                          Number 1107

                                       Konkoly Observatory
                                       Budapest
                                       1976 March 1


          THE PERIOD OF THE CEPHEID VARIABLE BD+56d 2806


         The variability of the star BD+56d 2806 (=HD 239994) was
    discovered by Fernie and Hube (1971). The type of the light variation 
    could not be determined on the basis of the observations.
    Nevertheless, this star was suspected to be a cepheid variable
    according to its location on the HR diagram.
         Afterwards Percy (1975) reobserved this variable during six
    consecutive nights. The star showed short period small amplitude
    light variation with period about three days.
        In order to determine a more correct value of the period;
    this star was observed in 1975-76. The observations were made in
    B and V colours close to the Johnson's system using the 24 in.
    and 20 in. telescopes of the Konkoly Observatory at Budapest and
    at the Piszkesteto Mountain Station, respectively. After transforming 
    to the Johnson's system the magnitudes are totally independent 
    of the telescope used.
         BD+56d 2815 was the comparison star. Its constancy was checked 
    by the star BD+56d 2808. Their adopted magnitudes are as follow:

                                    V   B-V
           comparison BD+56d 2815 8.67m 0.15
           check      BD+56d 2808 9.38  0.11

         The new observations made the determination of the period
    possible with accuracy of four decimal places. An improvement of
    the value of the period could be reached taking Percy's observations 
    into account. The correct value of the period is 2.80591d,
    thus the elements are:

               Max_hel = JD 2442676.397+2.80591d E

         The observations are listed in the Table. The Figure shows
    the V light curve. The starting epoch of the phase computation is
    JD 2430000. The amplitude of the light variation in V is 0.30m,
    and that of the B-V colour index is 0.15m. The observed light
    curve is almost complete. Unfortunately, there are fairly few 
    observations at the lower part of the rising branch, where one can
    suspect a small bump. The presence of the post-minimum bump seems
    to be a common feature of the small amplitude cepheids (Szabados
    1976).

                         [FIGURE 1]

JD 2442000+   deltaV  delta(B-V)   JD 2442000+   deltaV    delta(B-V)
     634.479  0.609    0.642         715.330      0.666    0.692
     635.405   .845     .699            .433       .643     .662
     636.519   .741     .662         720.376       .855     .739
     639.355   .709     .705         728.315       .869     .823
     640.358   .626     .677         738.372       .611     .648
     642.393   .633     .689         743.344       .656     .734
     645.477   .591     .642         756.239       .856     .815
     646.379   .807     .646         767.190       .831     .700
     669.406   .883     .794         770.195       .840     .791
     675.413   .822     .791         776.185       .887     .827
     676.397   .580     .682            .305       .875     .808
     685.490   .733     .667         777.271       .602     .678
     712.420   .700     .718         782.204       .882     .694
     714.374   .912     .767         787.202      0.885    0.720




                            L. SZABADOS

                          Konkoly Observatory
                          Budapest, Hungary




References:
 Fernie, J.D., Hube, J.C., ApJ. 168. 437, 1971. [BIBCODE 1971ApJ...168..437F ]
 Percy, J.R., IBVS No. 983, 1975
 Szabados, L., Budapest Mitteilungen (in preparation) 1976.